| Abstract: | The photopolymerizations of 4-vinylbenzophenone (VBP) in various solvents were investigated to make clear the photoininiation characteristics. It was found that direct photoirradiation produces polymers, oligomers (trimers), and dimers. The dimers were identified as trans- and cis-1,2-bis(4-benzoylphenyl)cyclobutanes. The fraction of trans-form in the cyclobutane dimers produced was about 80%, and was little affected by the reaction conditions. The quantum yields (VBP] = 0.1M in benzene) was estimated to be 3 × 10?2 for the dimerization and 2 × 10?4 for the initiation of polymerization. The photoreactions via π,π* triplet state of the monomer was suggested from the results. |
